In recent years, businesses offering rapid processing and printing of color print film, the “One Hour Photo” services, have proliferated. The commercial availability of the automated machines used for this rapid processing and printing, and their comparatively low cost have enabled many small business owners to enter the field, so that the photo finishing business is no longer confined to a few major commercial photo laboratories.
The processing equipment uses a variety of chemicals for film processing and printing. Each chemical is kept in a separate tank or reservoir from which it is pumped into the processing area of the machine at an appropriate time. The chemicals are preferably pumped through the machine in a continuous loop. The manufacturers supply directions as to the working life of each chemical agent, and directions as how to replenish the chemicals after a specified usage. In the course of processing and storage of the chemicals, various types of particulate matter, debris such as film fragments or paper fragments, aggregates of photographic chemicals, dirt, dust, or microorganisms such as algae or bacteria may contaminate the chemicals and their storage tanks. The presence of contaminants can damage film or prints being processed by scratching negatives or prints, causing losses that may require reprocessing or retouching, assuming such damage can be remedied. Contaminants may decrease the efficacy of the chemicals themselves, or clog up the processing equipment, resulting in lost time spent to clean the equipment.
Although disposable filters are available, their replacement cost over time can be significant. The cumulative disposal of filters also has a negative environmental impact. Conventional filters utilized in this equipment are also difficult to reuse because the filtration material is mounted on the inside of the filter. Consequently, these filters are difficult to thoroughly clean. Some of the materials used to manufacture these filters are subject to being washed off or damaged when subjected to cleaning, thus preventing their reuse.
One commercially available product employs a stainless steel filter tube that is fitted over a frame manufactured from an extruded plastic material. Although this filter fits on the frame like a sleeve, it is difficult to clean and maneuver into a good (i.e., fluid-tight) fit within the apparatus.
A further reusable filter is described in U.S. Pat. No. 6,105,787, to the present inventor, the entire contents of which is hereby incorporated by reference. The '787 patent describes a filtration device having a rigid tubular body that terminates in a pair of open ends. The body has a plurality of openings therein, leading to a bore, and a layer of a filtration material is stretched over the surface of the body. The filtration material is attached near the ends of the body, and a pair of end caps are glued within the ends. Although the filter described in the '787 patent has been successful, problems have arisen in maintaining consistency during production. More specifically, the filter is hand manufactured and thus each filter is slightly different in size, tightness of the filtration material, and the reliability of the glue attachment is compromised.
Thus, there is a need for a filtration device having a filter that is made of a filtration material that is reusable, that will not be washed off of its support matrix during cleaning, that will not be damaged from abrasion or cleansing agents during cleaning, and that can be economically manufactured with a high degree of quality control. Further, the filtration device should be made of materials capable of withstanding the physical conditions, including pressures, temperatures and flow rates, and chemical conditions of the environment of photographic processing chemicals in automated processing machines.